The present invention relates generally to a vibratory plow assembly which is adapted to lay cable, flexible pipe and the like underground in the cut made by a blade wherein the blade is vibrated to reduce the force required to pull the blade through the ground. More particularly, the present invention relates to a plow blade construction which provides for improved vibratory plowing.
Vibratory cable plows have been used for several years to lay cable, flexible pipe and the like underground. The cable or pipe may be either pulled through the cut of the plow blade or a cable chute may be provided on the trailing edge of the plow blade which guides the cable or pipe into the ground from a drum mounted on the tractor or other vehicle. Various types of vibrators have been mounted on the plow blade, or the vibrator and blade have been suspended together on a resilient frame assembly to generate either vertical or orbital motion in the plow blade. Examples of such prior art vibratory plows are disclosed in U.S. Pat. Nos. 4,040,261, 3,618,237 and 3,363,423, all assigned to the assignee of the present application.
Prior vibratory plow blades are generally straight in configuration and are inserted in the ground at a slight forward angle to create a downward reaction force to prevent rising of the blade as it is pulled through the ground. Alternatively, the blade may have a slight forward bend as its lowermost point for providing additional downward reaction force. However, this construction presents a problem in that the attached cable guide chute directs the cable in an opposite direction which places the cable at a substantial bend angle at the bottom of the blade cut due to the forward angle of the blade. Thus, there has been a need for a construction which requires less bend angle of the cable and reduces chute frictional drag.
While vibration of the plow blade of a cable laying plow results in several advantages including less ground disturbance and faster cable laying installation, it has now been discovered that the plow blade may be constructed in a way that adds to the efficiency of the vibratory plowing action. In particular, a plow blade constructed in accordance with the teachings of the present invention will substantially reduce the force required to cut the earth and pull the blade through the ground.